Despite a century of technological advances, drilling and construction of oil and gas wells remains a slow, dangerous, and expensive process. The costs associated with drilling some wells can exceed 100 million dollars. A significant contributor to these high costs is the suspension of drilling in order to repair geologically-related problem sections in wells. These problems can include, but are not limited to, lost-circulation, borehole instability, and well-pressure control. These problems are generally rectified by costly and time-consuming casing and cementing operations. Such conventional stabilization and sealing processes are required at each problem location, often dictating installation of a series of several diametrically descending, or telescopic-casing strings. Generally, a casing string formed of tube members is installed from the well surface to each problem zone; a 10,000-foot deep well often requires 20,000-30,000 feet of tube members because of overlapping sections.
Fluids such as oil, natural gas and water are generally obtained from a subterranean geologic formation (a “reservoir”) by drilling a well that penetrates the fluid-bearing formation. Once the well has been drilled to a certain depth, the well hole or borehole wall must be supported to prevent collapse. Conventional well drilling methods involve the installation of a casing string and cementing between the tube members and the borehole to provide support for the borehole structure. After cementing a casing string in place, the drilling to greater depths can commence. After each subsequent casing string is installed, the next drillbit must pass through the inner diameter of the casing. In this manner, each change in casing diameter requires a reduction in the borehole or wellhole diameter. This repeated reduction in the borehole diameter creates a need for very large initial borehole diameters to permit a reasonable pipe diameter at the depth where the wellbore penetrates the fluid-bearing formation. The need for larger boreholes and multiple casing strings results in more time, material and expense being used than if a uniform size borehole could be drilled from the surface to the fluid-bearing formation.
Various methods have been developed to stabilize or complete uncased boreholes. U.S. Pat. No. 5,348,095 discloses a method involving the radial expansion of a casing string to a configuration with a larger diameter. Very large forces are needed to impart the radial deformation desired in this method. In an effort to decrease the forces needed to expand the casing string, methods that involve expanding a liner that has longitudinal slots cut into it have been proposed (See U.S. Pat. Nos. 5,366,012 and 5,667,011). These methods involve the radial deformation of the slotted liner into a configuration with an increased diameter by running an expansion mandrel through the slotted liner. These methods still require significant amounts of force be applied throughout the entire length of the slotted liner.
During drilling of the borehole, drilling fluid is generally pumped through the drillstring to the lower end of the string. The drilling fluid then returns to the well surface via the annulus formed between the drillstring and the borehole wall. The circulating drilling fluid transports the drill cuttings to the well surface, controls the wellbore pressure, and cools the drillbit. A frequently encountered problem in the practice of drilling wellbores is leakage of drilling fluid from the borehole into the surrounding earth formation. Some leakage of the drilling fluid is generally considered allowable; however, in many instances the amount of leakage is such that further drilling is not allowable without first taking corrective measures. Such heavy drilling fluid losses can occur, for example, during drilling through depleted sandstone reservoirs and/or through unstable shales. Attempts have been made to stabilize shale problem regions by applying a drilling fluid having a relatively high specific weight. However, the weight of such heavy drilling fluid can be close to, or in excess of, the fracturing pressure of neighboring sandstone formations, thus causing damage to such formations.
Conventional corrective measures to address leakage of drilling fluid include pumping of lost circulation material (LCM) through the wellbore in order to plug the formation, pumping cement into the wellbore, or installing a casing or liner in the wellbore at the location of the fluid losses. The latter corrective action is the only feasible option where the fluid losses are severe. Traditionally, installing a casing or liner in the wellbore has been done by retrieving the drillstring from the wellbore or borehole and then running the casing/liner into the borehole, and thereafter cementing the casing/liner in place and waiting for the cement to harden. Such a process is a time consuming and costly procedure. Moreover, temporary measures to reduce the losses of drilling fluid to acceptable levels have to be taken before retrieving the drillstring from the borehole.
More recently, mechanical, or shape memory alloy or polymer (heat activated) expandable sleeves have been proposed; however, methods and devices for reliably deploying these expandable loss circulation patches have not been effectively demonstrated. The energy industry has pursued development of plastically-deformed expandable well-casings and single diameter well-casing systems (also known as “mono-diameter” or “mono-bore”) wherein a one size casing is used from the well surface to the target zone of the problem area, typically some 1-7 miles below the well surface. Single diameter well-casing systems can be used to replace former surface-to-problem-zone casing string installation with discrete-zone placement of an expandable casing. For example, a median casing size of 9⅝ inch outside diameter in an un-expanded state can be passed through a casing in the unexpanded state; the unexpanded casing can then be expanded to function in a nominal 10 inch to 12 inch borehole by means of a cold-work, mechanical steel deformation process performed in situ. The expanded casing assembly must, however, meet certain strength requirements and allow passage of subsequent 9⅝ inch outer diameter casing strings as drilling deepens and new problem zones are encountered.
This deforming process inherently requires use of relatively soft steels which may not provide the desired mechanical properties required in the environments of oil and gas wells. It is believed that most potential users cannot utilize current expandables due to fundamentally unsolvable technical or economic issues. For example, it is believed that conventional expandable tube members do not provide a good seal because they do not conform adequately to the irregular wall surfaces of wells when expanded. Expandable tube members that are made of steel materials have a natural tendency to “spring back” from their altered states after being expanded to their natural or original form. Spring back is also sometimes referred to as “recovery”, “resilience”, “elastic recovery”, “elastic hysteresis”, and/or “dynamic creep”. Spring back exists in all stages of worked materials. For pre-ruptured tube members, different degrees of deformity throughout the thickness of the tube-arc can translate into spring back rates that vary according to the severity of arc resulting from the deformation. As a result, it is believed that conventional expandable tube members can never properly form a seal in a problem area.
Furthermore, plastic deformation of the metal tube is achieved by forcing an expansion device, such as a plug or a mandrel, into the interior of the tube member to expand and deform the metal tube member. The expansion device can be (1) forced downward through the tube member to deform it, (2) pulled upward through the tube member to deform it, (3) rotated within the tube member to deform it, or (4) some combination thereof. The expansion device can also have tapered wedges or rollers to facilitate in the deformation of the tube member. It is known that high levels of deformity can cause stress-cracking in the tube member, a variety of metallurgical problems in the tube member, and/or decreased mechanical properties of the tube member after deformation.
A further disadvantage of presently known expandable tube members is that, as the tube member is deformed radially, such outward radial expansion causes the overall length of the tube member to be shortened by some 1% to 3% or more. Such shrinkage along the longitudinal axis of the tube member is undesirable. An inability to supply extra material to the shrinkage can impede radial expansion of the tube member. For example, if the pre-expanded casing becomes “stuck” or otherwise placed into tension longitudinally, the need to service the shrinkage cannot be met and the deforming material becomes prematurely strained. This is also a major source of difficulty when expanding threaded connections.
Expanding metallic pipe downhole in a well has become more common. Casing, slotted liners, and screens have been expanded using a variety of techniques involving fluid pressure or a swage. The expansion of tube members has to date excluded the use of composites. Composites offer advantages of light weight, good chemical and thermal resistance properties, and low cost. The problem with composites and other non-metallics is that they are too brittle to withstand the significant expansion that would make them useful in a downhole application where expansion was contemplated.
Prior attempts to use composites were not readily adapted for downhole use for a variety of reasons. One example is disclosed in U.S. Pat. No. 4,752,431 wherein a member is provided in a limp condition and unrolled. The member comprises a sandwich of a cement layer between two layers that could be flexible plastic, rubber or canvas. When water or steam is circulated, the limp member assumes a cylindrical shape and the cement sets to provide rigidity to the member to form a final tube member. The application of this technology is for lining existing pipes such as those that cross under roads. A stated advantage of this technology is that the limp member can follow the contour of the land and then be hardened when pressurized with water. However, prior to the member being formed and set, the member cannot function as a member that is used to conduct fluid into a well and/or provide other functions of tubular members in a well.
U.S. Pat. No. 5,634,743 uses a flexible lining that contains a curable synthetic resin in conjunction with a device advanced with the lining to apply ultrasonic energy to the leading end of the lining, as the lining is unfurled along the center of the pipe to be lined.
U.S. Pat. No. 5,925,409 teaches a multi-step procedure where a resin-containing hydrogen material is reacted with a polycarbodiimide to make a tube that can be inserted into another tube for the purpose of lining it. The inner tube is inflated to contact the outer tube and then cured in place with hot air or water, electricity, or radiation. The liner tube is inflated as opposed to expanded. A similar concept is employed in German App. No. DE 3732694 A1.
U.S. Publication No. 2001/0010781 A1 involves putting cables in a strip and then inflating a liner over the strip. The final step is to set the body with hot water in the liner or heat from cables that run through the body.
WO 93/15131 teaches a technique for lining sewer pipes and the like wherein the liner is applied followed by the application of ultrasonic energy to liberate a microencapsulated catalyst. Alternatively, iron oxide particles are incorporated in the resin and are heated by applying electromagnetic energy. No expansion is contemplated in this process. Related to this technique are U.S. Pat. Nos. 4,064,211; 4,680,066; and 4,770,562.
Elastic memory composites and their ability to be deformed on heating and to hold the deformed shape on subsequent cooling, have been described in “Developments in Elastic Memory Composite Materials for Spacecraft Deployable Structures”, IEEE (2001). These materials are disclosed as resuming their original shape when reheated. Shape memory materials and some of their uses are described in an article by Liang et al., “Investigation of Shape Memory Polymers and their Hybrid Composite”, Journal of Intelligent Materials Systems and Structures (April 1997). Also of interest is Murphey et al., “Some Micromechanics Considerations of the Folding of Rigidizable Composite Materials”, 19th AIAA Applied Aerodynamics Conference, Fluid Dynamics and Co-located Conferences https://doi.org/10.2514/6.2001-1418 (2001). Other patents of interest are U.S. Pat. Nos. 5,040,283; 5,186,215; 5,901,789; 6,752,208; 6,775,894; 7,104,317; 7,159,673; 7,478,686; 7,819,185; and 8,800,650.
Another problem with wells is that once a well is put in production, an influx of sand from the producing formation can lead to undesired fill within the wellbore and can thus damage valves and other production related equipment. Many methods have been attempted for sand control.
The present invention is directed to overcoming, or at least reducing, the effects of one or more of the problems set forth above, and can be useful in other applications as well.